The Alaska Department of Fish and Game has released its forecastfor next year’s sockeye salmon return.
2018 doesn’t project to be any better than a modest 2017, and somewhat below the 20 year average.
ADF&G is predicting a total sockeye return to Upper Cook Inlet of about 4.6 million. That’s within a range of between 3.6 and five and a half million. The department anticipates a commercial harvest of 1.9 million, down nearly a million from last year.
A lion’s share of those reds will come back to the Kenai river; about two and a half million. That’s more than a million fish less than the 20 year average for the Kenai. ADF&G commercial fisheries manager Pat Shields says there are a lot of variables from recent years that can help explain the lower projections. The brood years that will be represented by next year’s returning fish, each presented different challenges for those stocks.
“Each one of those years had unique environmental and other variables that affect the survival of the return from each of those brood years. When you have three brood years, you get a lot of variability in a run.”
Fish coming back next July will be four, five and six years old. Specifically on the Kenai river, the five year olds will likely be the biggest group. So, go back to 2013. What was life like for eggs laid that summer?
“We did measure a couple things that year that would indicate that the run would come back less than expected," Shields said.
"We had a warm summer that year, so the lake conditions in 2014, the first year of rearing, the turbidity in Skilak Lake was high because the glacier had melted quite a bit more due to the warm summer we had. High turbidity, meaning the water is more cloudy, results in less zooplankton production.”
Less zooplankton production means less food.
“And we measured that in the fry that were in the lake. They were smaller than average. When we have a smaller than average fry rearing in Skilak Lake, they survive at a lower rate. So we have some data that indicated the five year return in 2018 from the 2013 brood would be less than expected, and that’s part of the model.”
Those same factors, water temperature for instance, can have a different effect in a different part of the state. Like in Bristol Bay, which saw record returns last year, where warmer weather, and by extension, warmer lake water has actually helped. The warmer water means fish out there turn food into body mass faster. Healthier fish leaving for the ocean means more fish coming back years later. But, that same variable, warmth, translates much differently on the Kenai.
“We operate just kind of on the fringe, anyway, for sockeye production," Shields said.
"So any environmental condition that affects sockeye salmon in a negative sense, it can be significant in our runs. When we see real warm summers that melt glaciers that increase the turbidity of our lakes, it decreases our productivity and we end up with smaller runs. That’s one of the factors, it’s not the only one, it’s one of the factors that affect our sockeye salmon survival from year to year.”
For other rivers in Upper Cook Inlet, the model predicts a return to the Kasilof river about 866,000 sockeye. The Susitna river is expected to see 329,000, far below the 10 year average of almost 400,000.
Fish Creek, which drains into Knik Arm, is one home base that will likely see an increase over the long-term averages. More than 200,000 sockeye are expected back there, where the ten year average is well less than 100,000 fish.
Overall, Shields says he expects enough reds back for all user groups to fish, if not always with the results everyone would like.